Sugar-restricted diet hits certain cancers harder: Study
Research teams found the squamous cell carcinoma (SqCC), a type of lung cancer, used more sugar in its growth when compared to an adenocarcinoma (ADC), another non-small cell lung cancer.
“These findings lend credence to the idea that cancer is not just one disease, but many diseases that have very different characteristics,” said Dr Jung-whan "Jay" Kim, assistant professor of biological sciences at the University of Texas and senior author of the study.
“We'd like to know whether we might be able to affect cancer progression with dietary changes," he added.
Evidence is mounting over the last decade that certain types of cancer are more sugar-hungry than others are.
Its role in the nation’s health has formed the backdrop of policies designed to restrict its consumption amongst a country’s population.
Along with cancer, sugar is also linked to an increased risk of dental caries, overweight and cardio-metabolic risk factors and mortality.
Since 2014, Nordic Nutrition Recommendations have taken on board guidance, which recommends cutting sugar to less than 10% of total energy intake for children and adults.
The UK has adopted in 2015 an even more demanding threshold, with a recommended intake of less than 5% of dietary energy as free sugars.
Most other countries, such as the Netherlands, have not set quantitative reference intakes, but mention that 20% of the energy as added sugars may be detrimental to nutrition and health.
Greedy GLUT1
The study centres on the protein GLUT1 – a transporter responsible for carrying glucose into cells.
GLUT1 is also responsible for providing the sugar for energy that fuels cell metabolism, function and building cell membranes.
Experiments using human non-small cell lung cancer (NSCLC) tumour samples, patient-derived xenografts, mice models of NSCLC and NSCLC cell lines found an increased level of GLUT1 activity in the lung SqCC.
"We looked at this from several different experimental angles, and consistently, GLUT1 was highly active in the squamous subtype of cancer. Adenocarcinoma is much less dependent on sugar," Kim said.
"When we gave GLUT1 inhibitors to mice with lung cancer, the squamous cancer diminished, but not the adenocarcinoma," Kim said. "There was not a complete eradication, but tumour growth slowed.
Additional trials found GLUT1 levels to be elevated in a number of squamous cell cancers that include head and neck, oesophageal and cervical.
"These are very different organs and tissues in the body, but somehow squamous cell cancers have a very similar commonality in terms of glucose uptake," Kim said.
"This type of cancer clearly consumes a lot of sugar. One of our next steps is to look at why this is the case."
Sugar consumption levels
Despite government efforts, sugar consumption remains alarmingly high, particularly amongst children and young adults.
Worldwide intake of free sugars varies by age, setting and country.
In Europe, intake in adults ranges from about 7-8% of total energy intake in countries like Hungary and Norway, to 16-17% in countries like Spain and the UK.
Intake is much higher among children, ranging from about 12% in countries like Denmark, Slovenia and Sweden, to nearly 25% in Portugal.
Source: Nature Communications
Published online ahead of print: doi:10.1038/ncomms15503
“The distinct metabolic phenotype of lung squamous cell carcinoma defines selective vulnerability to glycolytic inhibition.”
Authors: Jung-whan Kim et al.
